Dork Eldar wrote:
Thanks for the fast and very detailed response!
I think that covers it. Feeling a little overwhelmed from all the rules, still haven't gotten battalions and allegiances and realm rules wrapped around my brain yet.
Your army needs an Allegiance. This is just the faction your army represents.
There are several tiers of allegiance. There are Grand Alliances, which are just very broad and cover one of Order, Chaos, Death, or Destruction. You can pick a more specific allegiance that is specific to proper fiction, such as Stormcast, Bonereapers etc. Normally there is one of these for each battletome. Then within a battletome there are often sub factions that represent organisations within the faction, such as the Hammers of Sigmar who are a particular group of Stormcast Eternals.
Generally speaking, the top level your allegiance is the more units you have to choose from, but the more specific it is the more powerful allegiance abilities you will unlock.
Battalions are quite complicated, but I'll go over the headlines. You do need to use Battalions at all, but if you do take any Battalions they are made up of a specific group of units in your army that you declare are in the Battalion. Every faction has their own specific Battalions, there are no generic one, and each one requires you to take a certain number of specific unit types to make up the Battalion. Battalions cost points in addition to the cost of the units in them, but for meeting these restrictions and paying the extra points you do get some benefits. Firstly, during deployment you put down all units from the same Battalion in one go, which is very useful as the first player to finish deployment will normally choose who goes first. Second you get an extra Command Point and an extra Artefact to use in your army. Third you will get access to extra special abilities specific to each Battalion.
As a very rough rule of thumb, in a 2k game you are probably going to want a Battalion and you probably don't want more than one. This is because the extra points you could be spending on actual models adds up quickly! At 1k or lower its rarely worth using Battalions at all. But this will all depend a lot on what army you are playing and what you are trying to do. Some Battalions are MUCH better than others, and some armies generally have better quality options here than others.
Hope that all helps!